Bone screw and method of manufacture

ABSTRACT

A bone screw comprises a shaft defining a longitudinal axis and a minor diameter. The shaft including a core having an angled surface relative to the axis. The angled surface extending from the minor diameter adjacent a proximal portion of the shaft to a distal portion of the shaft, and a wall disposed about the angled surface. The wall including at least one thread having an external thread form. In some embodiments, systems, spinal constructs, surgical instruments and methods are disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/975,389, filed May 9, 2018, which is expressly incorporated byreference herein, in its entirety.

TECHNICAL FIELD

The present disclosure generally relates to medical devices for thetreatment of spinal disorders, and more particularly to a spinal implantsystem having spinal implants manufactured by a method including aplurality of manufacturing techniques.

BACKGROUND

Spinal pathologies and disorders such as scoliosis and other curvatureabnormalities, kyphosis, degenerative disc disease, disc herniation,osteoporosis, spondylolisthesis, stenosis, tumor, and fracture mayresult from factors including trauma, disease and degenerativeconditions caused by injury and aging. Spinal disorders typically resultin symptoms including deformity, pain, nerve damage, and partial orcomplete loss of mobility.

Non-surgical treatments, such as medication, rehabilitation and exercisecan be effective, however, may fail to relieve the symptoms associatedwith these disorders. Surgical treatment of these spinal disordersincludes correction, fusion, fixation, discectomy, laminectomy andimplantable prosthetics. As part of these surgical treatments, spinalconstructs including bone fasteners are often used to provide stabilityto a treated region. Such bone fasteners are traditionally manufacturedusing a medical machining technique. This disclosure describes animprovement over these prior technologies.

SUMMARY

In one embodiment, a bone screw is provided. The bone screw comprises ashaft defining a longitudinal axis and a minor diameter. The shaftincluding a core having an angled surface relative to the axis. Theangled surface extending from the minor diameter adjacent a proximalportion of the shaft to a distal portion of the shaft, and a walldisposed about the angled surface. The wall including at least onethread having an external thread form. In some embodiments, systems,spinal constructs, spinal implants, surgical instruments and methods aredisclosed.

In one embodiment, the bone screw comprises a shaft defining alongitudinal axis and a minor diameter. The shaft including a corehaving an angled surface relative to the axis. The angled surfaceextending from the minor diameter adjacent a proximal portion of theshaft to a distal portion of the shaft, and a wall disposed about theangled surface. The wall including at least one thread having anexternal thread form. The thread form along a proximal portion of thewall includes a solid configuration relative to the thread form along adistal portion of the wall.

In one embodiment, the bone screw comprises a shaft defining alongitudinal axis and a minor diameter. The shaft including a corehaving an angled surface relative to the axis, the angled surfaceextending from the minor diameter adjacent a proximal portion of theshaft to a distal portion of the shaft, and a wall disposed about theangled surface. The wall including at least one thread having anexternal thread form. The proximal portion being formed by asubtractive, deformative or transformative manufacturing method toinclude a first thread form and define a distal end. The distal portionbeing formed onto the distal end in a layer by layer formation by anadditive manufacturing method, the distal portion including a corehaving an angled surface relative to the axis and a wall disposed aboutthe angled surface. The wall including at least one thread having anexternal thread form.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more readily apparent from thespecific description accompanied by the following drawings, in which:

FIG. 1 is a side view of components of one embodiment of a system inaccordance with the principles of the present disclosure;

FIG. 2 is a side view of components of the system shown in FIG. 1 ;

FIG. 3 is a side cross section view of components of the system shown inFIG. 1 ;

FIG. 4 is a break away cross section view of components of oneembodiment of a system in accordance with the principles of the presentdisclosure; and

FIG. 5 is a break away perspective view of components of one embodimentof a system in accordance with the principles of the present disclosure.

DETAILED DESCRIPTION

The exemplary embodiments of a surgical system and related methods ofuse disclosed are discussed in terms of medical devices for thetreatment of musculoskeletal disorders and more particularly, in termsof a spinal implant having a structurally optimized internal structureto enhance the mechanical properties of the bone screw.

In some embodiments, the spinal implant system of the present disclosurecomprises a bone screw having internal features to structurally optimizethe mechanical properties of the bone screw that combines amanufacturing method, such as, for example, one or more traditionalmanufacturing features and materials and a manufacturing method, suchas, for example, one or more additive manufacturing features andmaterials. In some embodiments, the bone screw is configured withinternal features, such as, for example, various forms and/or patterns.In some embodiments, the internal features may be homogeneous. In someembodiments, the internal features are configured to optimize bone screwfunction by increasing bone screw rigidity and/or increasing bone screwstrength. In some embodiments, the internal features are configured toprovide deflection in selected areas of the bone screw.

In some embodiments, the spinal implant system of the present disclosurecomprises a bone screw having a solid core that includes a variedconfiguration to optimize bone screw function. In some embodiments, thefeatures of the bone screw can be created and/or altered throughadditive manufacturing. In some embodiments, the features can bemanufactured to minimize material usage. In some embodiments, theconfiguration of the solid core is configured to provide deflection inselected areas of the bone screw. In some embodiments, the bone screwincludes features, such as, for example, struts, braces and/or honeycombpatterns of material within the body of the bone screw. In someembodiments, the features include porous and/or trabecular material. Insome embodiments, the bone screw includes an internal solid strutconfigured to reinforce a load bearing portion of the bone screw.

In some embodiments, the spinal implant system of the present disclosureis configured to enhance fixation of bone screws with bone. In someembodiments, the spinal implant system of the present disclosureincludes a spinal implant configured for engagement with cortical boneand cancellous bone within the vertebra. In some embodiments, the spinalimplant system of the present disclosure is configured to resist and/orprevent toggle on a bone screw when the bone screw is engaged with densecortical bone and a less dense cancellous bone resulting from a load onthe bone screw. In some embodiments, the spinal implant system of thepresent disclosure is configured to resist and/or prevent loosening ofthe bone screw from the cortical bone and in some instances, pull outfrom the vertebra. In some embodiments, the spinal implant system of thepresent disclosure is configured to facilitate bone through-growth toprovide for an improved bone attachment to the bone screw. In someembodiments, the bone screw is anchored in the bone thereby reducingpull out.

In some embodiments, the spinal implant system comprises a spinalimplant having a hybrid configuration that combines a manufacturingmethod, such as, for example, one or more traditional manufacturingfeatures and materials and a manufacturing method, such as, for example,one or more additive manufacturing features and materials. In someembodiments, additive manufacturing includes 3-D printing. In someembodiments, additive manufacturing includes fused deposition modeling,selective laser sintering, direct metal laser sintering, selective lasermelting, electron beam melting, layered object manufacturing andstereolithography. In some embodiments, additive manufacturing includesrapid prototyping, desktop manufacturing, direct manufacturing, directdigital manufacturing, digital fabrication, instant manufacturing andon-demand manufacturing. In some embodiments, the spinal implant systemcomprises a spinal implant being manufactured by a fully additiveprocess and grown or otherwise printed.

In some embodiments, the spinal implant system of the present disclosurecomprises a spinal implant, such as, for example, a bone screwmanufactured by combining traditional manufacturing methods and additivemanufacturing methods. In some embodiments, the bone screw ismanufactured by applying additive manufacturing material in areas wherethe bone screw can benefit from materials and properties of additivemanufacturing. In some embodiments, traditional materials are utilizedwhere the benefits of these materials, such as physical properties andcost, are superior to those resulting from additive manufacturingfeatures and materials.

In some embodiments, the spinal implants, surgical instruments and/ormedical devices of the present disclosure may be employed to treatspinal disorders such as, for example, degenerative disc disease, discherniation, osteoporosis, spondylolisthesis, stenosis, scoliosis andother curvature abnormalities, kyphosis, tumor and fractures. In someembodiments, the spinal implants, surgical instruments and/or medicaldevices of the present disclosure may be employed with other osteal andbone related applications, including those associated with diagnosticsand therapeutics. In some embodiments, the spinal implants, surgicalinstruments and/or medical devices of the present disclosure may bealternatively employed in a surgical treatment with a patient in a proneor supine position, and/or employ various surgical approaches to thespine, including anterior, posterior, posterior mid-line, lateral,postero-lateral, and/or antero-lateral approaches, and in other bodyregions such as maxillofacial and extremities. The spinal implants,surgical instruments and/or medical devices of the present disclosuremay also be alternatively employed with procedures for treating thelumbar, cervical, thoracic, sacral and pelvic regions of a spinalcolumn. The spinal implants, surgical instruments and/or medical devicesof the present disclosure may also be used on animals, bone models andother non-living substrates, such as, for example, in training, testingand demonstration.

The present disclosure may be understood more readily by reference tothe following detailed description of the embodiments taken inconnection with the accompanying drawing figures, which form a part ofthis disclosure. It is to be understood that this application is notlimited to the specific devices, methods, conditions or parametersdescribed and/or shown herein, and that the terminology used herein isfor the purpose of describing particular embodiments by way of exampleonly and is not intended to be limiting. In some embodiments, as used inthe specification and including the appended claims, the singular forms“a,” “an,” and “the” include the plural, and reference to a particularnumerical value includes at least that particular value, unless thecontext clearly dictates otherwise. Ranges may be expressed herein asfrom “about” or “approximately” one particular value and/or to “about”or “approximately” another particular value. When such a range isexpressed, another embodiment includes from the one particular valueand/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another embodiment. It isalso understood that all spatial references, such as, for example,horizontal, vertical, top, upper, lower, bottom, left and right, are forillustrative purposes only and can be varied within the scope of thedisclosure. For example, the references “upper” and “lower” are relativeand used only in the context to the other, and are not necessarily“superior” and “inferior”.

As used in the specification and including the appended claims,“treating” or “treatment” of a disease or condition refers to performinga procedure that may include administering one or more drugs to apatient (human, normal or otherwise or other mammal), employingimplantable devices, and/or employing instruments that treat thedisease, such as, for example, microdiscectomy instruments used toremove portions bulging or herniated discs and/or bone spurs, in aneffort to alleviate signs or symptoms of the disease or condition.Alleviation can occur prior to signs or symptoms of the disease orcondition appearing, as well as after their appearance. Thus, treatingor treatment includes preventing or prevention of disease or undesirablecondition (e.g., preventing the disease from occurring in a patient, whomay be predisposed to the disease but has not yet been diagnosed ashaving it). In addition, treating or treatment does not require completealleviation of signs or symptoms, does not require a cure, andspecifically includes procedures that have only a marginal effect on thepatient. Treatment can include inhibiting the disease, e.g., arrestingits development, or relieving the disease, e.g., causing regression ofthe disease. For example, treatment can include reducing acute orchronic inflammation; alleviating pain and mitigating and inducingre-growth of new ligament, bone and other tissues; as an adjunct insurgery; and/or any repair procedure. Also, as used in the specificationand including the appended claims, the term “tissue” includes softtissue, ligaments, tendons, cartilage and/or bone unless specificallyreferred to otherwise.

The following discussion includes a description of a spinal implant, amethod of manufacturing a spinal implant, related components and methodsof employing the surgical system in accordance with the principles ofthe present disclosure. Alternate embodiments are disclosed. Referenceis made in detail to the exemplary embodiments of the presentdisclosure, which are illustrated in the accompanying figures. Turningto FIGS. 1-3 , there are illustrated components of a spinal implantsystem 10 including spinal implants, surgical instruments and medicaldevices.

The components of spinal implant system 10 can be fabricated frombiologically acceptable materials suitable for medical applications,including metals, synthetic polymers, ceramics and bone material and/ortheir composites. For example, the components of spinal implant system10, individually or collectively, can be fabricated from materials suchas stainless steel alloys, aluminum, commercially pure titanium,titanium alloys, Grade 5 titanium, super-elastic titanium alloys,cobalt-chrome alloys, superelastic metallic alloys (e.g., Nitinol, superelasto-plastic metals, such as GUM METAL®), ceramics and compositesthereof such as calcium phosphate (e.g., SKELITE™), thermoplastics suchas polyaryletherketone (PAEK) including polyetheretherketone (PEEK),polyetherketoneketone (PEKK) and polyetherketone (PEK), carbon-PEEKcomposites, PEEK-BaSO₄ polymeric rubbers, polyethylene terephthalate(PET), fabric, silicone, polyurethane, silicone-polyurethane copolymers,polymeric rubbers, polyolefin rubbers, hydrogels, semi-rigid and rigidmaterials, elastomers, rubbers, thermoplastic elastomers, thermosetelastomers, elastomeric composites, rigid polymers includingpolyphenylene, polyimide, polyimide, polyetherimide, polyethylene,epoxy, bone material including autograft, allograft, xenograft ortransgenic cortical and/or corticocancellous bone, and tissue growth ordifferentiation factors, partially resorbable materials, such as, forexample, composites of metals and calcium-based ceramics, composites ofPEEK and calcium based ceramics, composites of PEEK with resorbablepolymers, totally resorbable materials, such as, for example, calciumbased ceramics such as calcium phosphate, tri-calcium phosphate (TCP),hydroxyapatite (HA)-TCP, calcium sulfate, or other resorbable polymerssuch as polyaetide, polyglycolide, polytyrosine carbonate,polycaroplaetohe and their combinations.

Various components of spinal implant system 10 may have materialcomposites, including the above materials, to achieve various desiredcharacteristics such as strength, rigidity, elasticity, compliance,biomechanical performance, durability and radiolucency or imagingpreference. The components of spinal implant system 10, individually orcollectively, may also be fabricated from a heterogeneous material suchas a combination of two or more of the above-described materials. Thecomponents of spinal implant system 10 may be monolithically formed,integrally connected or include fastening elements and/or instruments,as described herein.

Spinal implant system 10 includes a spinal implant comprising a bonefastener, such as, for example, a bone screw 12. In some embodiments,bone screw 12 includes variable, alternate, different and/or transitionportions to optimize bone growth and/or fixation with tissue. In someembodiments, the portions of bone screw 12 can include a variable innercore. In some embodiments, the inner core is tapered to selectivelyprovide a point of controlled deflection within bone screw 12 to resistand/or prevent pull out, toggle or fatigue fracture of bone screw 12. Insome embodiments, the portions of bone screw 12 can include an internalsolid strut. In some embodiments, the portions of bone screw 12 caninclude a variable section thread and a solid strut. In someembodiments, the portions of bone screw 12 can include one or morecavities, for example, one or more pathways, openings, lattice and/orscaffold. In some embodiments, bone screw 12 can include even,uninterrupted portions, portions that are continuous and without cavityand/or solid portions. In some embodiments, bone screw 12 can includeroughened portions, porous portions, trabecular portions and/orhoneycomb portions. In some embodiments, bone screw 12 can includeroughened portions, porous portions, trabecular portions and/orhoneycomb portions. In some embodiments, bone screw 12 allows bonegrowth therethrough such that bone is allowed to connect through bonescrew 12.

Bone screw 12 defines a longitudinal axis X1. Bone screw 12 includes ascrew shaft 18 having a proximal portion 14 and a distal portion 16. Insome embodiments, bone screw 12 is manufactured by a manufacturingprocess to enhance fixation and/or facilitate bone growth, as describedherein. In some embodiments, bone screw 12 is manufactured by anadditive manufacturing method. In some embodiments, proximal portion 14is fabricated by a first manufacturing method and distal portion 16fabricated by a second manufacturing method to enhance fixation and/orfacilitate bone growth, as described herein.

In some embodiments, the manufacturing method can include a traditionalmachining method, such as, for example, subtractive, deformative ortransformative manufacturing methods. In some embodiments, thetraditional manufacturing method may include cutting, grinding, rolling,forming, molding, casting, forging, extruding, whirling, grinding and/orcold working. In some embodiments, the traditional manufacturing methodincludes portion 14 being formed by a medical machining process. In someembodiments, medical machining processes can include use of computernumerical control (CNC) high speed milling machines, Swiss machiningdevices, CNC turning with living tooling and/or wire EDM 4th axis. Insome embodiments, the manufacturing method for fabricating portion 14includes a finishing process, such as, for example, laser marking,tumble blasting, bead blasting, micro blasting and/or powder blasting.

For example, portion 14 is formed by a manufacturing method, whichincludes feeding a wire, rod, bar, or wire or rod bar stock into amachine that cuts the wire at a designated length to form a screw blankand then forms a head of the screw blank into a selected configuration.Portion 14 is manufactured to include a head 20 and a portion of screwshaft 18. Portion 14 extends between an end 24 and an end 26. End 24includes head 20.

Portion 14 includes threads 28, which are fabricated by traditionalmachining methods, as described herein. Threads 28 extend along all or aportion of portion 14. Threads 28 are oriented with portion 14 anddisposed for engagement with tissue. In some embodiments, threads 28include a fine, closely-spaced configuration and/or shallowconfiguration to facilitate and/or enhance engagement with tissue. Insome embodiments, threads 28 include a smaller pitch or more threadturns per axial distance to provide a stronger fixation with tissueand/or resist loosening from tissue. In some embodiments, threads 28include an increased greater pitch and an equal lead between threadturns. In some embodiments, threads 28 are continuous along portion 14.In some embodiments, threads 28 are continuous along shaft 18 via asecond manufacturing method, as described herein. In some embodiments,threads 28 may be intermittent, staggered, discontinuous and/or mayinclude a single thread turn or a plurality of discrete threads. In someembodiments, other penetrating elements may be located on and/ormanufactured with portion 14, such as, for example, a nailconfiguration, barbs, expanding elements, raised elements, ribs, and/orspikes to facilitate engagement of portion 14 with tissue.

End 26 includes a surface 30 that defines a distal end 32. In someembodiments, surface 30 may be disposed along a length of portion 14 orat a distalmost surface of portion 14. In some embodiments, distal end32 extends perpendicular to axis X1. In some embodiments, distal end 32may be disposed in various orientations relative to axis X1, such as,for example, transverse and/or at angular orientations, such as acute orobtuse. In one embodiment, distal end 32 is disposed at an acute angularorientation relative to axis X1.

Distal end 32 is configured for providing a fabrication platform forforming portion 16 thereon with an additive manufacturing method, asdescribed herein. Distal end 32 has a substantially planar configurationfor material deposition and/or heating during an additive manufacturingprocess for fabricating portion 16 onto distal end 32. In someembodiments, all or only a portion of distal end 32 may have alternatesurface configurations, such as, for example, angled, irregular,uniform, non-uniform, offset, staggered, tapered, arcuate, undulating,mesh, porous, semi-porous, dimpled, pointed and/or textured. In someembodiments, distal end 32 may include a nail configuration, barbs,expanding elements, raised elements, ribs, and/or spikes to provide afabrication platform for forming portion 16 thereon with an additivemanufacturing method, as described herein. In some embodiments, all oronly a portion of distal end 32 may have alternate cross sectionconfigurations, such as, for example, oval, oblong triangular, square,polygonal, irregular, uniform, non-uniform, offset, staggered, and/ortapered.

Turning to FIG. 3 , portion 16 is fabricated with a second manufacturingmethod by disposing a material onto distal end 32, as described herein.Portion 16 is configured for fabrication on distal end 32 such thatportion 16 is fused with surface 30. Portion 16 is formed on distal end32 by an additive manufacturing method. Portion 16 is formed on distalend 32 to extend between an end 40 and end 42 according to instructionsreceived from the computer and processor, and end 40 is fused withsurface 30. Portion 16 is fabricated according to instructions receivedfrom the computer and processor based on the digital rendering and/ordata of the selected configuration, via the additive manufacturingprocess described herein to include a thread 76 that extends between end40 and a distal tip 44. In some embodiments, portion 14 is formed on anend of portion 16. In some embodiments, portion 14 is formed on an endof head 20.

Portion 16 includes a wall 50 having a surface 52. In some embodiments,wall 50 extends circumferentially to define portion 16. In someembodiments, wall 50 is disposed about an inner core 54, as describedherein. In various embodiments, inner core 54 has a variableconfiguration, as described herein. In some embodiments, wall 50 definesa thickness, which may be uniform, undulating, tapered, increasing,decreasing, variable, offset, stepped, arcuate, angled and/or staggered.In some embodiments, surface 52 may be rough, textured, porous,semi-porous, dimpled, knurled, toothed, grooved and/or polished.

Core 54 has a variable configuration and includes a tapered surface 90to facilitate fixation with tissue. Surface 90 is angled at an angle Arelative to axis X1. In various embodiments, surface 90 extends from aminor diameter MD1 of screw 12. In some embodiments, surface 90 startsto extend from minor diameter MD1 at or adjacent where proximal portion14 meets the distal portion 16. In various embodiments, the surface 90extends from the minor diameter, distally, through distal portion 16.Surface 90 extends along all or a portion of core 54. Surface 90 isangled relative to axis X1 to define a tapered cross section. In someembodiments, surface 90 is uniformly tapered. In a contemplatedembodiment, the surface 90 does not taper uniformly, such as by angle Abeing different along various points along the screw 12. Variables for adesigner to consider in determining whether and how to taper include abalance between any of strength for insertion of the screw 12 (e.g.,torque strength), strength against breaking after implanted, andnon-solid real estate for promoting bone growth into the screw (i.e.,into lattice 56. As an example, a designer may determine that core 54being thicker proximally by a certain amount versus distally isappropriate to provide sufficient strength for insertion, wherein morestrength may be determined needed in more proximal portions of the screw12 than distally, where less strength is needed, and more lattice can beprovided for more bone growth after implantation. Other variablesinclude other supporting structure 12 of the screw, such asconfiguration of the thread form, such as whether fully or partiallysolid or non-solid. Other varying core widths, shapes, and angling cansimilarly be determined preferable to balance any of these or other suchvariables. In some embodiments, surface 90 may have variousconfigurations, such as, for example, cylindrical, round, oval, oblong,triangular, polygonal having planar or arcuate side portions, irregular,uniform, non-uniform, consistent, variable, horseshoe shape, U-shape orkidney bean shape. In some embodiments, surface 90 defines a crosssection of core 54 that decreases in diameter CD from end 40 to distaltip 44. In a contemplated embodiment, the core 54 tapers distally towardthe tip 44 to a zero or near-zero diameter. In some embodiments, surface90 defines a cross section of core 54 that increases distally indiameter.

Core 54 is configured to provide a selected point of deflection withinbone screw 12. For example, bone screws 12 are subjected to variousloads when implanted with tissue, such as, for example, vertebrae. Core54 is tapered to optimize the deflection of bone screw 12 when underloads, for example, an axial load or a cantilever load applied byvertebrae to resist and/or prevent pull-out. In some embodiments, core54 is configured to provide an increased resistance to bending and/orlateral torsional buckling. In some embodiments, core 54 reduces theeffects of shear stresses on bone screw 12. In some embodiments, core 54is configured to reduce an angle of twist.

Core 54 extends within distal portion 16 and includes a solidconfiguration. In some embodiments, core 54 is continuous, or solid,without any internal openings and/or cavities. In some embodiments, core54 includes a material having a closely compacted structure. In someembodiments, core 54 includes a solid configuration, which may include arange of density including 0.5 through 10.5 grams per cubic centimeter.In some embodiments, core 54 includes a density that is greater than adensity of lattice 56.

In some embodiments, core 54 may include a porous configurationconfigured to facilitate bone growth. In some embodiments, the porousconfiguration may include a range of porosity over a wide range ofeffective pore sizes. In some embodiments, core 54 includes a trabecularconfiguration. In some embodiments, the trabecular configuration mayinclude a density similar to cancellous or cortical bone tissue.

Surface 52 includes a non-solid configuration, such as, for example, alattice 56. In some embodiments, the non-solid configuration may includea porous structure and/or a trabecular configuration. Disclosures hereininvolving a lattice, or other particular type of non-solid structure,are meant to disclose at the same time analogous embodiments in whichother non-solid structure in addition or instead of the particular typeof structure.

In various embodiments, the non-solid configuration is configured toprovide one or a plurality of pathways to facilitate bone through growthwithin, and in some embodiments all of the way through, from one surfaceto an opposite surface of bone screw 12. Lattice 56 is continuous alongsurface 52 of portion 16 between end 40 and distal tip 44. In someembodiments, lattice 56 extends along all or a portion of inner core 54.Thread 46 is connected with lattice 56 to facilitate fixation of threads46 with tissue. In some embodiments, lattice 56 may include one or moreportions, layers and/or substrates. In some embodiments, one or moreportions, layers and/or substrates of lattice 56 may be disposed side byside, offset, staggered, stepped, tapered, end to end, spaced apart, inseries and/or in parallel. In some embodiments, lattice 56 defines athickness, which may be uniform, undulating, tapered, increasing,decreasing, variable, offset, stepped, arcuate, angled and/or staggered.In some embodiments, one or more layers of lattice 56 are disposed in aside by side, parallel orientation within wall 50. Lattice 56 includesone or more layers of a matrix of material.

In some embodiments, lattice 56 includes a plurality of nodes 64 andopenings 66, which can be disposed in rows and columns, and/or in arandom configuration. In some embodiments, nodes 64 and openings 66 aredisposed in a series orientation. In some embodiments, nodes 64 andopenings 66 are disposed in a parallel orientation.

In some embodiments, lattice 56 may form a rasp-like configuration. Insome embodiments, lattice 56 is configured to engage tissue, such as,for example, cortical bone and/or cancellous bone, such as, to cut,shave, shear, incise and/or disrupt such tissue. In some embodiments,all or a portion of each lattice 56 may have various configurations,such as, for example, cylindrical, round, oval, oblong, triangular,polygonal having planar or arcuate side portions, irregular, uniform,non-uniform, consistent, variable, horseshoe shape, U-shape or kidneybean shape. In some embodiments, lattice 56 may be rough, textured,porous, semi-porous, dimpled, knurled, toothed, grooved and/or polishedto facilitate engagement and cutting of tissue. In some embodiments,lattice 56 forms a tunnel configured to guide, drive and/or direct thecut tissue into openings 66 to facilitate fusion of bone screw 12 withtissue, such as, for example, vertebrae. In some embodiments, wall 50includes a trabecular configuration.

Thread 76 has a variable configuration and includes an external threadform 78. Thread form 78 has a flank 79 extending between a root R and acrest C. Thread 76 includes an external thread form 78. Flank 79 has avariable configuration and includes a portion 80 and a portion 82 tofacilitate bone growth and/or fixation with tissue. Portion 80 extendscircumferentially about root R and includes a lattice configuration tofacilitate fusion of bone screw 12 with tissue, as described herein.Portion 80 transitions from lattice 56 such that wall 50 and portion 82are homogenous. In some embodiments, portion 80 includes a trabecularconfiguration. In some embodiments, the trabecular configuration mayinclude a density similar to cancellous or cortical bone tissue. In someembodiments, portion 80 includes a porous configuration. In someembodiments, the porous configuration may include a range of porosityover a wide range of effective pore sizes. In some embodiments, theporous configuration of portion 16 may have macroporosity, mesoporosity,microporosity and nanoporosity.

A surface 88 of the lattice of portion 80 is configured to engagetissue, such as, for example, cortical bone and/or cancellous bone, suchas, to cut, shave, shear, incise and/or disrupt such tissue. In someembodiments, all or a portion of surface 88 may have variousconfigurations, such as, for example, cylindrical, round, oval, oblong,triangular, polygonal having planar or arcuate side portions, irregular,uniform, non-uniform, consistent, variable, horseshoe shape, U-shape orkidney bean shape. In some embodiments, surface 88 may be rough,textured, porous, semi-porous, dimpled, knurled, toothed, grooved and/orpolished to facilitate engagement and cutting of tissue.

Portion 82 defines an even, uninterrupted edge surface of thread form78, and includes an even, solid surface relative to portion 80, whichprovides a variable configuration of thread form 78. Portion 82 extendsalong crest C forming an edge surface of thread form 78 that transitionsfrom portion 80 and is configured to resist and/or prevent damage totissue during insertion and/or engagement of bone screw 12 with tissue.Portion 82 is configured to resist and/or prevent damage to nerves, thedura and/or blood vessels. In some embodiments, portion 82 is continuouswithout any openings and/or cavities. In some embodiments, portion 82includes a material having a closely compacted structure. In someembodiments, portion 82 includes a solid configuration, which mayinclude a range of density including 0.5 through 10.5 grams per cubiccentimeter. In some embodiments, portion 82 includes a density that isgreater than a density of portion 80.

In some embodiments, thread 76 is fabricated to include a fine,closely-spaced and/or shallow configuration to facilitate and/or enhanceengagement with tissue. In some embodiments, thread 76 is fabricated toinclude an increased pitch and an equal lead between thread turns thanthread 28, as shown in FIG. 1 . In some embodiments, thread 76 isfabricated to include a smaller pitch or more thread turns per axialdistance than thread 28 to provide a stronger fixation with tissueand/or resist loosening from tissue. In some embodiments, thread 76 isfabricated to be continuous along portion 16. In some embodiments,thread 76 is fabricated to be continuous along portion 16. In someembodiments, thread 76 is fabricated to be intermittent, staggered,discontinuous and/or may include a single thread turn or a plurality ofdiscrete threads. In some embodiments, portion 16 is fabricated toinclude penetrating elements, such as, for example, a nailconfiguration, barbs, expanding elements, raised elements, ribs, and/orspikes. In some embodiments, thread 46 is fabricated to be self-tappingor intermittent at distal tip 44. In some embodiments, distal tip 44 maybe rounded. In some embodiments, distal tip 44 may be self-drilling. Insome embodiments, distal tip 44 includes a solid outer surface.

For example, manipulation of bone screw 12, including rotation and/ortranslation causes lattice 56 to cut tissue and/or shave bone such thatthe cut tissue is guided and/or directed into openings 66 to promotebone growth and enhance fusion of bone screw 12. In some embodiments,external grating materials or biologics may be prepacked with bone screw12. Core 54 is configured to allow bone screw 12 to respond to loadsapplied by vertebrae and/or other implants by providing selecteddeflection to resist and/or prevent bone screw 12 pull out from tissue.

In some embodiments, additive manufacturing includes 3-D printing, asdescribed herein. In some embodiments, additive manufacturing includesfused deposition modeling, selective laser sintering, direct metal lasersintering, selective laser melting, electron beam melting, layeredobject manufacturing and stereolithography. In some embodiments,additive manufacturing includes rapid prototyping, desktopmanufacturing, direct manufacturing, direct digital manufacturing,digital fabrication, instant manufacturing or on-demand manufacturing.In some embodiments, portion 16 is manufactured by additivemanufacturing, as described herein, and mechanically attached withsurface 30 by, for example, welding, threading, adhesives and/orstaking.

In one embodiment, one or more manufacturing methods for fabricatingdistal portion 16, proximal portion 14 and/or other components of bonescrew 12 include imaging patient anatomy with imaging techniques, suchas, for example, x-ray, fluoroscopy, computed tomography (CT), magneticresonance imaging (MRI), surgical navigation, bone density (DEXA) and/oracquirable 2-D or 3-D images of patient anatomy. Selected configurationparameters of distal portion 16, proximal portion 14 and/or othercomponents of bone screw 12 are collected, calculated and/or determined.Such configuration parameters can include one or more of patient anatomyimaging, surgical treatment, historical patient data, statistical data,treatment algorithms, implant material, implant dimensions, porosityand/or manufacturing method. In some embodiments, the configurationparameters can include implant material and porosity of distal portion16 determined based on patient anatomy and the surgical treatment. Insome embodiments, the implant material includes a selected porosity ofdistal portion 16, as described herein. In some embodiments, theselected configuration parameters of distal portion 16, proximal portion14 and/or other components of bone screw 12 are patient specific. Insome embodiments, the selected configuration parameters of distalportion 16, proximal portion 14 and/or other components of bone screw 12are based on generic or standard configurations and/or sizes and notpatient specific. In some embodiments, the selected configurationparameters of distal portion 16, proximal portion 14 and/or othercomponents of bone screw 12 are based on one or more configurationsand/or sizes of components of a kit of spinal implant system 10 and notpatient specific.

For example, based on one or more selected configuration parameters, asdescribed herein, a digital rendering and/or data of a selected distalportion 16, proximal portion 14 and/or other components of bone screw12, which can include a 2-D or a 3-D digital model and/or image, iscollected, calculated and/or determined, and generated for display froma graphical user interface, as described herein, and/or storage on adatabase attached to a computer and a processor (not shown), asdescribed herein. In some embodiments, the computer provides the abilityto display, via a monitor, as well as save, digitally manipulate, orprint a hard copy of the digital rendering and/or data. In someembodiments, a selected distal portion 16, proximal portion 14 and/orother components of bone screw 12 can be designed virtually in thecomputer with a CAD/CAM program, which is on a computer display. In someembodiments, the processor may execute codes stored in acomputer-readable memory medium to execute one or more instructions ofthe computer, for example, to transmit instructions to an additivemanufacturing device, such as, for example, a 3-D printer. In someembodiments, the database and/or computer-readable medium may includeRAM, ROM, EPROM, magnetic, optical, digital, electromagnetic, flashdrive and/or semiconductor technology. In some embodiments, theprocessor can instruct motors (not shown) that control movement androtation of spinal implant system 10 components, for example, a buildplate, distal end 32 and/or laser emitting devices, as described herein.

Portion 14 is fabricated with threads 28 by a first manufacturingmethod, as described herein. Portion 14 is connected with a part, suchas, for example, a build plate in connection with an additive formingprocess and a second manufacturing method for fabricating distal portion16. Portion 16 is built up layer by layer and the melting process isrepeated slice by slice, layer by layer, until the final layer of amaterial is melted and portion 16 is complete. Portion 16 is formed ondistal end 32 to extend between an end 40 and end 42 according toinstructions received from the computer and processor, and end 40 isfused with surface 30. In some embodiments, the material is subjected todirect metal laser sintering (DMLS®), selective laser sintering (SLS),fused deposition modeling (FDM), or fused filament fabrication (FFF), orstereolithography (SLA).

In some embodiments, portion 16 is fabricated in a configuration havinga porosity via the additive manufacturing method, as described herein.In some embodiments, portion 16 is fabricated having a porosity with aporogen that is spheroidal, cuboidal, rectangular, elongated, tubular,fibrous, disc-shaped, platelet-shaped, polygonal or a mixture thereof.In some embodiments, a porosity of portion 16 is based on a plurality ofmacropores, micropores, nanopores structures and/or a combinationthereof.

In some embodiments, bone screw 12 includes an implant receiver (notshown) connectable with head 20. In some embodiments, bone screw 12 caninclude various configurations, such as, for example, a posted screw, apedicle screw, a bolt, a bone screw for a lateral plate, an interbodyscrew, a uni-axial screw, a fixed angle screw, a multi-axial screw, aside loading screw, a sagittal adjusting screw, a transverse sagittaladjusting screw, an awl tip, a dual rod multi-axial screw, midlinelumbar fusion screw and/or a sacral bone screw. In some embodiments, theimplant receiver can be attached by manual engagement and/ornon-instrumented assembly, which may include a practitioner, surgeonand/or medical staff grasping the implant receiver and shaft 18 andforcibly snap or pop fitting the components together. In someembodiments, spinal implant system 10 comprises a kit including aplurality of bone screws 12 of varying configuration, as describedherein. In some embodiments, bone screw 12 is selected from the kit andemployed with a treatment at the surgical site.

In one embodiment, bone screw 12 is fabricated to define a passagewaythrough all or a portion of shaft 18 such that bone screw 12 includes acannulated configuration and a plurality of lateral fenestrations incommunication with the passageway.

In assembly, operation and use, spinal implant system 10 is employed totreat an affected section of vertebrae. A medical practitioner obtainsaccess to a surgical site including the vertebrae in any appropriatemanner, such as through incision and retraction of tissues. Thecomponents of surgical system 10 including bone screw 12 are employed toaugment a surgical treatment. Bone screw 12 can be delivered to asurgical site as a pre-assembled device or can be assembled in situ.Spinal implant system 10 may be may be completely or partially revised,removed or replaced.

Surgical system 10 may be used with surgical methods or techniquesincluding open surgery, mini-open surgery, minimally invasive surgeryand percutaneous surgical implantation, whereby the vertebrae isaccessed through a mini-incision, or sleeve that provides a protectedpassageway to the area. Once access to the surgical site is obtained, asurgical treatment, for example, corpectomy and/or discectomy, can beperformed for treating a spine disorder.

Bone screw 12 is connected with a surgical instrument, such as, forexample, a driver (not shown) and is delivered to the surgical site.Bone screw 12 is manipulated including rotation and/or translation forengagement with cortical bone and/or cancellous bone. Manipulation ofbone screw 12 causes lattice 56 to cut tissue and/or shave bone suchthat the cut tissue is guided and/or directed into openings 66 topromote bone growth and enhance fusion of bone screw 12. Core 54 isconfigured to allow bone screw 12 to respond to loads applied byvertebrae and/or other implants by providing selected deflection toresist and/or prevent bone screw 12 pull out from tissue.

In one embodiment, as shown in FIG. 4 , spinal implant system 10,similar to the systems and methods described herein, includes a bonescrew 112, similar to bone screw 12 described herein. Bone screw 112includes portion 14, as described herein, and a portion 116.

Portion 116 includes a wall 150, similar to wall 50 described herein,having a non-solid configuration, as described herein, such as, forexample, a lattice 156, similar to lattice 56 described herein. Wall 150extends about a solid inner core 154, similar to core 54 as describedherein. Portion 116 includes a thread 176. Thread 176 has a variableconfiguration, as described herein, and includes an external thread form178. Thread form 178 includes a flank 179, similar to flank 79 asdescribed herein.

Flank 179 has a variable configuration and includes a trailing edge 180and a leading edge 182 to facilitate bone growth and/or fixation withtissue. Trailing edge 180 defines an even, uninterrupted edge surface ofthread form 178, and includes an even, solid surface relative to portion182, which provides a variable configuration of thread form 178.Trailing edge 180 transitions from inner core 154 such that inner core154 and trailing edge 180 are homogenous. In some embodiments, trailingedge 180 is continuous without any openings and/or cavities, asdescribed herein.

Leading edge 182 includes a lattice configuration to facilitate fusionof bone screw 112 with tissue, as described herein. Leading edge 182transitions from lattice 156 such that wall 150 and leading edge 182 arehomogenous. In some embodiments, leading edge 182 includes a trabecularconfiguration. In some embodiments, leading edge 182 is continuouswithout any openings and/or cavities, as described herein, and trailingedge 180 includes a lattice configuration.

In some embodiments, portion 116 is formed on distal end 32 by anadditive manufacturing method, as described herein. In some embodiments,portion 116 is fabricated according to instructions received from thecomputer and processor based on the digital rendering and/or data of theselected configuration, via the additive manufacturing process, asdescribed herein. Portion 116 is configured for fabrication on distalend 32 such that portion 116 is fused with surface 30, as describedherein.

In one embodiment, as shown in FIG. 5 , spinal implant system 10,similar to the systems and methods described herein, includes a bonescrew 212, similar to bone screw 12 described herein. Bone screw 212includes portion 14, as described herein, and a portion 216.

Portion 216 includes a variable configuration, as described herein, andincludes a wall 250. Wall 250 extends about a solid inner core 254,similar to core 54 as described herein. Portion 216 includes a thread276 having an external thread form 278. Thread form 278 includes a flank279, similar to flank 79 as described herein.

Wall 250 has a variable configuration and includes a portion 280 and aportion 282 to facilitate bone growth and/or fixation with tissue.Portion 280 includes a plurality of struts 284 that extend along portion216. Struts 284 are circumferentially disposed about portion 216 anddefine a cavity 286 therebetween. Struts 284 include an even, solidsurface relative to portion 282, as described herein. Struts 274transition from inner core 254 to reinforce thread 276 to resist and/orprevent pull-out.

Struts 284 include a tapered flange 288. Flange 288 extends along all ora portion of flank 279, which provides a variable configuration ofthread form 278. Flange 288 extends between an end 300 and an end 302.Flange 288 includes an increase in diameter from end 300 to end 302 tosupport and/or strengthen thread form 278.

Portion 282 includes lattice 286, similar to lattice 56 as describedherein. Portion 282 is disposed with cavities 286 such that lattice 286is non-continuous along portion 216 forming the variable configurationof wall 250. Lattice 286 extends along all or a portion of flank 279,which provides a variable configuration of thread form 278 with struts284. In some embodiments, portion 282 includes a trabecularconfiguration, as described herein.

In some embodiments, portion 216 is formed on distal end 32 by anadditive manufacturing method, as described herein. In some embodiments,portion 216 is fabricated according to instructions received from thecomputer and processor based on the digital rendering and/or data of theselected configuration, via the additive manufacturing process, asdescribed herein. Portion 216 is configured for fabrication on distalend 32 such that portion 216 is fused with surface 30, as describedherein

It will be understood that various modifications may be made to theembodiments disclosed herein. Therefore, the above description shouldnot be construed as limiting, but merely as exemplification of thevarious embodiments. Those skilled in the art will envision othermodifications within the scope and spirit of the claims appended hereto.

What is claimed is:
 1. A bone screw comprising a shaft defining alongitudinal axis, the shaft including a proximal portion and a distalportion, the proximal portion comprising a first thread, the firstthread being made entirely from a first material, the distal portionhaving a taper, the first material being non-porous, the distal portioncomprising a core, the shaft including a wall having a surface and athickness disposed about the core, the wall defining a plurality ofspaced apart struts, the shaft comprising a lattice positioned betweenthe struts, the struts having a solid surface relative to the lattice,the distal portion comprising a second thread, a portion of the secondthread extending outwardly from the wall, the second thread comprising asecond material, the second material being porous.
 2. The bone screwrecited in claim 1, wherein the second thread is made from the firstmaterial and the second material.
 3. The bone screw recited in claim 1,wherein a root of the second thread is made from the first material anda crest of the second thread is made from the second material.
 4. Thebone screw recited in claim 3, wherein the wall is made from the secondmaterial.
 5. The bone screw recited in claim 1, wherein a root of thesecond thread is made entirely from the first material and a crest ofthe second thread is made entirely from the second material.
 6. The bonescrew recited in claim 5, wherein the wall is made entirely from thesecond material.
 7. The bone screw recited in claim 1, wherein a root ofthe second thread is made from the first material and a crest of thesecond thread includes a leading portion and a trailing portion, theleading portion being made from the second material, the trailingportion being made from the first material.
 8. The bone screw recited inclaim 7, wherein the wall is made from the second material.
 9. The bonescrew recited in claim 1, wherein a root of the second thread is madeentirely from the first material and a crest of the second threadincludes a leading portion and a trailing portion, the leading portionbeing made entirely from the second material, the trailing portion beingmade entirely from the first material.
 10. The bone screw recited inclaim 9, wherein the wall is made entirely from the second material. 11.The bone screw recited in claim 1, wherein the core is tapered along thelongitudinal axis.
 12. The bone screw recited in claim 1, wherein thefirst thread includes a pitch and the second thread includes anincreased pitch and an equal lead between thread turns.
 13. The bonescrew recited in claim 1, further comprising a head coupled to theproximal portion, the head being substantially spherical and including aplurality of ridges.
 14. The bone screw recited in claim 1, furthercomprising a head coupled to the proximal portion, the head having amaximum diameter greater than a maximum diameter of the shaft.
 15. Thebone screw recited in claim 1, wherein the first material has a firstdensity and the second material has a second density, the second densitybeing less than the first density.
 16. The bone screw recited in claim1, wherein the first material has a density between 0.5 through 10.5grams per cubic centimeter and the second material has a density lessthan the density of the first material.
 17. The bone screw recited inclaim 1, wherein the bone screw defines a minor diameter, a surface ofthe core extending from the minor diameter, distally, through the distalportion.
 18. The bone screw recited in claim 1, wherein the bone screwis non-cannulated.
 19. A bone screw comprising a shaft defining alongitudinal axis, the shaft including a proximal portion and a distalportion, the proximal portion comprising a first thread, the firstthread being made entirely from a first material, the distal portioncomprising a core, the shaft including a wall having a surface and athickness disposed about the core, the wall defining a plurality ofspaced apart struts, the shaft comprising a lattice positioned betweenthe struts, the struts having a solid surface relative to the lattice,the distal portion comprising a second thread, the struts each extendingbetween adjacent crests of the second thread, a portion of the secondthread extending outwardly from the wall, the first thread including apitch and the second thread including an increased pitch and an equallead between thread turns, a root of the second thread is made from thefirst material and a crest of the second thread includes a leadingportion and a trailing portion, the leading portion being made from asecond material, the trailing portion being made from the firstmaterial, the second material being porous, the second material having adensity less than a density of the first material.
 20. A bone screwcomprising a shaft defining a longitudinal axis, the shaft including aproximal portion and a distal portion, the proximal portion comprising afirst thread, the first thread being made entirely from a firstmaterial, the distal portion comprising a core, the shaft including awall having a surface and a thickness disposed about the core, the walldefining a plurality of spaced apart struts, the shaft comprising alattice positioned between the struts, the struts having a solid surfacerelative to the lattice, the distal portion comprising a second thread,the struts each extending between adjacent crests of the second thread,a portion of the second thread extending outwardly from the wall, thefirst thread including a pitch and the second thread including anincreased pitch and an equal lead between thread turns, a root of thesecond thread is made from the first material and a crest of the secondthread includes a leading portion and a trailing portion, the leadingportion being made from a second material, the trailing portion beingmade from the first material, the second material being porous, thefirst material having a density between 0.5 through 10.5 grams per cubiccentimeter, the second material having a density similar to cancellousbone tissue, the density of the second material being less than thedensity of the first material.